VOYAGER 1 NEAR THE HELIOPAUSE
VOYAGER 1 NEAR THE HELIOPAUSE
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DOI：
10.1088/2041-8205/783/1/l16
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发表时间：
2014-03-01
影响因子：
7.9
通讯作者：
Pogorelov, N. V.
中科院分区：
文献类型：
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作者：
Borovikov, S. N.;Pogorelov, N. V.
最近来自旅行者1号宇宙飞船的观测表明，它正在对本地星际介质（LISM）进行采样。这是相当令人惊讶的，因为没有一个现实的，太阳风（SW）与LISM相互作用的稳态模型给出一个像30 AU这样窄的内部日鞘宽度。这包括假设在拾取离子分布函数中离子能量向尾部的强再分配的模型。我们的研究表明，将SW与LISM分开的日球层顶（HP）不是一个光滑的切向不连续，而是一个受瑞利-泰勒型不稳定性影响的表面，这可能导致LISM物质穿透SW深处。我们还表明，HP侧翼总是受到开尔文-亥姆霍兹不稳定性的影响。在稳态模型中，这种不稳定性在HP鼻翼附近被日球层磁场显著抑制，但在太阳周期效应的存在下表现出来。我们认为旅行者1号可能处于这样一个不稳定的区域，因此观测到的等离子体密度要比原始的西南偏南高得多。这些结果也许可以解释旅行者1号早期进入LISM的原因。他们还表明，在航天器最终离开日球层之前，有可能再次开始对西南偏南进行采样。
Recent observations from the Voyager 1 spacecraft show that it is sampling the local interstellar medium (LISM). This is quite surprising because no realistic, steady-state model of the solar wind (SW) interaction with the LISM gives an inner heliosheath width as narrow as similar to 30 AU. This includes models that assume a strong redistribution of the ion energy to the tails in the pickup ion distribution function. We show that the heliopause (HP), which separates the SW from the LISM, is not a smooth tangential discontinuity, but rather a surface subject to Rayleigh-Taylor-type instabilities which can result in LISM material penetration deep inside the SW. We also show that the HP flanks are always subject to a Kelvin-Helmholtz instability. The instabilities are considerably suppressed near the HP nose by the heliospheric magnetic field in steady-state models, but reveal themselves in the presence of solar cycle effects. We argue that Voyager 1 may be in one such instability region and is therefore observing plasma densities much higher than those in the pristine SW. These results may explain the early penetration of Voyager 1 into the LISM. They also show that there is a possibility that the spacecraft may start sampling the SW again before it finally leaves the heliosphere.